Mold cleaning system

ABSTRACT

Provided is a mold cleaning system. On the basis of an identification mark assigned to a mold and detected by a mark detector when cleaning the mold, the mold cleaning system obtains shape data for the molding surface of the mold which is stored in a database, and on the basis of the obtained shape data, the mold cleaning system controls the movement of arms using the control device, moves a laser head along the molding surface thereof while irradiating with a laser beam supplied by a laser oscillator, and as a result, removes the dirt adhered to the molding surface.

TECHNICAL FIELD

The present technology relates to a mold cleaning system; andparticularly relates to a mold cleaning system which makes it possibleto prevent scratches on a molding surface while efficiently removingdirt therefrom without requiring a hand operation by a person, even formolds having complicated molding-surface shapes.

BACKGROUND ART

Dirt derived from rubber components or compounding agents is adheredslightly to a molding surface of a mold for vulcanizing rubber productssuch as tires every time the vulcanization is performed. Since the dirtgradually accumulates as the mold is used repeatedly, leaving the dirtas it is negatively impacts the quality of the products to bevulcanized. Thus, as appropriate, the dirt needs to be removed bycleaning the molding surface. Examples of known mold cleaning methodsinclude a shot blasting cleaning method, a laser beam cleaning method,and a plasma cleaning method.

With the shot blasting cleaning method, the molding surface is easy tobe scratched. Thus, to prevent scratches on the molding surface causedby the cleaning, it is desirable to use the laser beam cleaning methodin which the molding surface is irradiated with a laser beam and thedirt is removed by the shock wave caused by the irradiation, or to usethe plasma cleaning method in which the dirt is removed with thechemical reaction of the dirt caused by a generated plasma. However, anarea that the plasma cleaning method can clean in a unit time is small.Therefore, the laser beam cleaning method is more desirable consideringefficiency.

Various mold cleaning methods using laser beam have been proposed (forexample, see Japanese Unexamined Patent Application Publication Nos.2008-62633A and 2004-167744A). In the cleaning method disclosed inJapanese Unexamined Patent Application Publication No. 2008-62633A, thedirt is removed by irradiating, from a laser head, the molding surfaceof the mold with a laser beam (CO₂ laser beam) supplied from a laseroscillator. At this time, an arm (manipulator) that moves the laser headis controlled by the original shape data (CAD data etc.) of the mold anda position correction means for the laser head and the arm moves thelaser head along concaves and convexes on the molding surface (seeparagraphs [0011] and [0021] to [0025] etc. of Japanese UnexaminedPatent Application Publication No. 2008-62633A).

However, the molding surface of the mold is not always formed in thesame shape but is formed in various shapes. Thus, in the methoddisclosed in Japanese Unexamined Patent Application Publication No.2008-62633A, to clean molds having different molding-surface shapes, anoperation for invoking the original shape data of the mold stored in acontrol device is required every time the mold cleaning is performed. Inthe case of tire vulcanization molds for which there are numerous typesof molding-surface shapes, there is a problem that a checking if themold to be cleaned and the original shape data therefor correspond toeach other is required every time the cleaning is performed and therebythe operation becomes complicated.

In the cleaning method disclosed in Japanese Unexamined PatentApplication Publication No. 2004-167744A, a laser irradiator is fixed toa predetermined position, and a mold is rotated to move the mold so thatthe mold surface changes from a vertical posture into a slanting posturewith respect to the optical axis of the laser beam. A process such asteaching this motion in advance is required to rotate the mold in thisway.

SUMMARY

The present technology provides a mold cleaning system which makes itpossible to prevent scratches on a molding surface while efficientlyremoving dirt therefrom without requiring a hand operation by a person,even for molds having complicated molding-surface shapes.

Solution to Problem

A mold cleaning system of the present technology is provided with alaser oscillator, a laser head configured to irradiate a molding surfaceof a mold with a laser beam from the laser oscillator, an arm configuredto move the laser head freely in three dimensions, a control deviceconfigured to control the motion of the arm, a database in which anidentification mark assigned to each mold to be cleaned to identify themold, and shape data for the molding surface of the mold to which theidentification mark is assigned are stored in advance in associationwith each other; and a mark detector configured to detect theidentification mark. The shape data for the molding surface of the moldstored in the database is obtained on the basis of the identificationmark assigned to the mold and detected by the mark detector when themold is cleaned. By controlling the motion of the arm on the basis ofthe obtained shape data, the laser head is moved along the moldingsurface while irradiating with the laser beam to clean the moldingsurface.

According to the present technology, the identification mark assigned tothe mold to be cleaned is detected by the mark detector when the mold iscleaned, and the shape data for the molding surface of the mold storedin the database is automatically obtained on the basis of the detectedidentification mark. Thus, it is no longer required to perform manualoperations for invoking the shape data for the molding surface of themold to be cleaned and to check the correspondence relation between theactual mold and the shape data every time the cleaning is performed.Also, since the laser head is moved along the molding surface on thebasis of the shape data obtained from the database while irradiatingwith the laser beam to clean the molding surface, it is possible toprevent scratches on the molding surface while efficiently removing thedirt therefrom without requiring a hand operation by a person, even formolds having complicated molding-surface shapes.

For example, the mold cleaning system can also be provided with a cameraconfigured to obtain image data for the molding surface. The moldcleaning system can also be configured to grasp a cleaning state of themolding surface on the basis of the image data obtained by the camera,store the grasped cleaning state and position information of the moldingsurface in the control device, and, for the positions on the moldingsurface in which the grasped cleaning state does not satisfy a presetstandard, perform cleaning again by irradiating with the laser beam fromthe laser head. With this configuration, only the positions (range) thatare particularly dirty are re-cleaned later, which is advantageous forremoving the dirt efficiently and cleanly.

The mold cleaning system can also be provided with a plurality of laserheads having different laser irradiation widths as the laser head. Themold cleaning system can also be configured to perform cleaning forparticular preset portions by using a laser head having a relativelysmall laser irradiation width or by using a laser head having arelatively large laser irradiation width with the laser head having arelatively small laser irradiation width. With this configuration, thecleaning can be finished in a short time by using the laser head havinga relatively large laser irradiation width for relatively flat and wideportions. Meanwhile, for portions in which concaves and convexes existcomplicatedly in a narrow range on the molding surface, the portionshaving complicated shapes can be evenly irradiated with the laser beamby using the laser head having a relatively small laser irradiationwidth, and as a result, the dirt can be removed cleanly.

The mold cleaning system can also be provided with a temperature sensorconfigured to successively detect a temperature of the molding surfacethat is irradiated with the laser beam. The mold cleaning system canalso be configured to suspend an irradiation with the laser beam whenthe temperature detected by the temperature sensor exceeds a presetacceptable temperature. With this configuration, the molding surface canbe avoided from being overheated by the irradiated laser beam. As such,a defect that the molding surface is thermally deformed by the laserbeam can be prevented.

Although studless-tire vulcanization molds have complicatedmolding-surface shapes and cast splicing molds for pneumatic tirevulcanization have small gaps defined on the molding surfaces thereof,by applying the present technology, scratches in the molding surfacescan be prevented while efficiently removing the dirt therefrom.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory drawing illustrating a mold cleaning system ofthe present technology as viewed in a plan view.

FIG. 2 is an explanatory drawing illustrating a molding surface of astudless-tire vulcanization mold as viewed in a plan view.

FIG. 3 is an explanatory drawing illustrating a molding surface of acast splicing mold as viewed in an enlarged cross-section.

FIG. 4 is an explanatory drawing illustrating a laser head and a mold tobe cleaned as viewed in a side view.

FIG. 5 is an explanatory drawing illustrating a laser head and a mold tobe cleaned as viewed in a front view.

DETAILED DESCRIPTION

A mold cleaning system of the present technology will now be describedon the basis of the embodiments illustrated in the drawings.

Although a tire vulcanization mold is to be cleaned in the followingdescription, the present technology can also be used to clean molds forvulcanizing other rubber products than tires.

A mold cleaning system 1 of the present technology illustrated in FIG. 1is provided with a laser oscillator 2, a laser head 4, an arm 6 to whichthe laser head 4 is attached, a control device 7 that controls themotion of the arm 6, a database 8, and a mark detector 3 a. In thisembodiment, the mold cleaning system 1 is further provided with a camera3 b that obtains image data for a molding surface 12 of a mold 11, and atemperature sensor 3 c that successively detects a temperature of themolding surface 12 that is irradiated with a laser beam L. The detectiondata detected by the mark detector 3 a, the image data obtained by thecamera 3 b, and the temperature data detected by the temperature sensor3 c are input to the control device 7.

The main components of the cleaning system 1 except for the laseroscillator 2 are disposed in a cleaning booth 9, which becomes a closedspace. The cleaning booth 9 is provided with an inlet door 9 a and anoutlet door 9 b and has a structure that becomes a closed space and canshield the laser beam L when the inlet door 9 a and the outlet door 9 bare closed.

The inlet door 9 a is connected with a carrying-in conveyor apparatus 10a and the outlet door 9 b is connected with a carrying-out conveyorapparatus 10 c. The space between the carrying-in conveyor apparatus 10a and the carrying-out conveyor apparatus 10 c becomes an internal spaceof the cleaning booth 9 and a processing conveyor apparatus 10 b isdisposed at this position. In this embodiment, the processing conveyorapparatus 10 b is bent and extended to be an arc shape. The mold 11 tobe cleaned is placed on the carrying-in conveyor apparatus 10 a and thecleaned mold 11 is placed on the carrying-out conveyor apparatus 10 c.The processing conveyor apparatus 10 b functions as a processing tablewhen the mold 11 is cleaned.

The laser oscillator 2 and the laser head 4 are connected by an opticalfiber cable 2 a. The laser beam L supplied by the laser oscillator 2 istransmitted to the laser head 4 through the optical fiber cable 2 a. Inthe present technology, it is preferable to use a YAG laser beam as thelaser beam L.

The molding surface 12 of the mold 11 is irradiated with the laser beamL by the laser head 4. The arm 6 is rotatably attached to an arm base 5and is configured by rotatably connecting a plurality of arm parts 6 a,6 b. The laser head 4 is removably attached to the tip of the arm 6.Therefore, the laser head 4 can be moved freely in three dimensions bycontrolling the motion of the arm 6.

In this embodiment, a plurality of laser heads 4 a, 4 b having differentlaser irradiation widths are provided as illustrated in FIG. 4. One isthe laser head 4 a having a relatively large laser irradiation width andthe other is the laser head 4 b having a relatively small laserirradiation width. The laser head 4 a has a configuration in which agalvano mirror is incorporated and the laser beam L can be scanned in awidth direction and a wider range can be irradiated with the laser beamL. The laser irradiation width is variable (for example, from 4 to 70mm). The other laser head 4 b irradiates a pinpoint with the laser beamL. A plurality of the laser heads 4 a having variable laser irradiationwidths may be provided to use a different laser irradiation width foreach laser head. For example, the oscillating frequency of the laseroscillator 2 is from 10 to 40 kHz. The frequency in which the laser beamL is scanned from the laser head 4 a in the width direction is, forexample, from 20 to 150 Hz.

A database 8 is disposed in a storage unit of the control device 7. Eachof the molds 11 to be cleaned is assigned an identification mark D toidentify the mold 11. The identification mark D is assigned to the mold11 by engraving or by attaching a label or the like. The identificationmark D is configured with, for example, numbers, characters, or acombination thereof.

In the database 8, shape data for the molding surface 12 of each mold 11is stored. Each shape data is stored in the database 11 with theidentification mark D assigned to the mold 11 having the molding surface12 based on that shape data. That is, in the database 8, the shape datafor the molding surface 12 of the mold 11 to which the identificationmark D is assigned and the identification mark D are stored in advancein association with each other.

The mold 11 to be cleaned is not only a normal type mold but also, forexample, a studless-tire vulcanization mold illustrated in FIG. 2.Groove forming projections 13 and sipe forming projections 14 areprojected on the molding surface 12 of the mold 11. The groove formingprojections 13 are casted integrally with the base material of the mold11 and the sipe forming projections 14 are separately attached to themolding surface 12. The base material of the mold 11 is usually made ofaluminum and the sipe forming projections 14 are made of steel or thelike.

The thickness of the sipe forming projections 14 is about from 0.4 to1.2 mm. The groove forming projections 13 may be thin depending on atread pattern of a tire, for example, in the case of a complicated treadpattern. Thus, the sipe forming projections 14 or thin groove formingprojections 13 are the parts that are easy to be scratched when the moldis cleaned. It is noted that a C arrow, an R arrow, and a W arrowdescribed in FIG. 2, FIG. 4, and FIG. 5 respectively indicate acircumferential direction, a radius direction, and a width direction ofa tire that is to be inserted into the mold 11 and vulcanized therein.

Another example of the type of mold 11 to be cleaned is a cast splicingmold for pneumatic tire vulcanization illustrated in FIG. 3. The mold 11is produced by so-called cast splicing in which a first casting part 15is casted and a second casting part 16 is casted thereafter. By thesolidification and shrinkage of a casted melting metal, a small gap g isdefined in a cast splicing part M between the first casting part 15 andthe second casting part 16. The size of the small gap g is, for example,from 5 to 80 μm. An exhaust hole 17 in communication with the small gapg is defined. In the mold 11, unnecessary air or gas when the tire isvulcanized is discharged from the molding surface 12 to the exhaust hole17 through the small gap g, and then discharged out of the mold 11through the exhaust hole 17. The small gap g is a part that is easy tobe scratched when the mold is cleaned.

A procedure for cleaning the molding surface 12 of the mold 11 by usingthe cleaning system 1 will now be described.

First, the mold 11 to be cleaned is placed on the carrying-in conveyorapparatus 10 a. Next, the inlet door 9 a is opened, and the carrying-inconveyor apparatus 10 a and the processing conveyor apparatus 10 b areoperated to move the mold 11 to be cleaned onto the processing conveyorapparatus 10 b and position the mold 11 at a predetermined position.Then, the inlet door 9 a is closed so that the cleaning booth 9 becomesa closed space. Provided here is an interlocking structure in which thelaser oscillator 2 is not actuated until the cleaning booth 9 becomes aclosed space.

Next, the identification mark D assigned to the mold 11 is detected bythe mark detector 3 a. On the basis of the detected identification markD, the shape data for the molding surface 12 of the mold 11 stored inthe database 8 is automatically obtained.

Next, the motion of the arm 6 is controlled on the basis of the obtainedshape data for the molding surface 12 of the mold 11 to move the laserhead 4 along the molding surface 12 as illustrated in FIG. 4 and FIG. 5.While the laser head 4 is being moved in this way, the molding surface12 is irradiated with the laser beam L supplied from the laseroscillator 2. The dirt X adhered to the molding surface 12 is removedand cleaned by the emitted laser beam L.

To restrict irradiation unevenness of the laser beam L, the movementdirection of the laser head 4 and the irradiation direction of the laserbeam L are controlled while keeping the spacing between the tip of thelaser head 4 and the opposing molding surface 12 as constant aspossible. The movement velocity of the laser head 4 is kept as constantas possible, and the laser head 4 is moved to cover the range to becleaned.

In this embodiment, although two laser heads 4 a, 4 b are used togetherto irradiate with the laser beam L, it is also possible to use eitherone of the laser heads 4 and the other laser head 4 thereafter. Forexample, the molding surface 12 is irradiated with the laser beam L bymoving the laser head 4 a having a relatively large laser irradiationwidth to cover the range to be cleaned, and then, the molding surface 12is irradiated with the laser beam L by using the laser head 4 b having arelatively small laser irradiation width.

As described above, according to the present technology, the shape datafor the molding surface 12 of the mold 11 stored in the database 8 isautomatically obtained on the basis of the identification mark Ddetected by the mark detector 3 a when the mold 11 is cleaned. Thus,even when many molds 11 having different molding surfaces 12 are to becleaned, it is no longer required to perform manual operations forinvoking the shape data for the molding surface 12 of the mold 11 to becleaned and checking the correspondence relation between the actual moldand the shape data every time the cleaning is performed.

And, since the laser head 4 is moved along the molding surface 12 on thebasis of the shape data obtained from the database 8 while irradiatedwith the laser beam, it is possible to prevent scratches on the moldingsurface 12 while efficiently removing the dirt X therefrom withoutrequiring a hand operation by a person, even for molds 11 having themolding surfaces 12 with complicated shapes, such as studless-tirevulcanization molds or cast splicing molds for pneumatic tirevulcanization.

In this embodiment, the image data for the cleaned molding surface 12 isobtained by the camera 3 b, and the cleaning state of the moldingsurface 12 is grasped on the basis of the obtained image data. Thegrasped cleaning state and the position information of the moldingsurface are stored in the control device 7. After irradiating the entirerange of the molding surface 12 with the laser beam L, for the positionsof the molding surface 12 in which the grasped cleaning state does notsatisfy a preset standard, the cleaning is performed again by moving thelaser head 4 to the positions and irradiating with the laser beam L. Itis also possible to provide a configuration in which the mark detector 3a has the function of the camera 3 b and concurrently serves as bothdevices.

A standard for determining whether the cleaning state is appropriate(dirt X has been removed) or inappropriate (dirt X is remaining) isinput and set to the control device 7 in advance. By using the controldevice 7, whether the grasped cleaning state satisfies the presetstandard is determined.

The standard for determining the cleaning state is set on the basis of,for example, a color density of the image data for the molding surface12 obtained by the camera 3 b. If the density is greater than a certaindegree, the cleaning state indicating that the dirt X is remaining isset. Alternatively, it is possible to obtain the image data for themolding surface 12 immediately before and immediately after the laserbeam L is emitted, compare these image data, and set the standard on thebasis of the change in the color density. If the color density has notchanged or the degree of the change is small, the cleaning stateindicating that the dirt X is remaining is set. With this configuration,only the positions (range) that are particularly dirty are re-cleanedlater, which is advantageous for removing the dirt X efficiently andcleanly.

It is also possible to input and set particular portions to the controldevice 7 in advance, and for the preset particular portions, performcleaning by using the laser head 4 b having a relatively small laserirradiation width or by using the laser head 4 a having a relativelylarge laser irradiation width with the laser head 4 b having arelatively small laser irradiation width. Examples of the particularportions include a range having a complicated shape such as a rangearound the bottom of the sipe forming projections 14 illustrated in FIG.2, or the inner circumferential surface of the small gap g in the castsplicing part M illustrated in FIG. 3.

With this configuration, the cleaning can be finished in a short timefor relatively flat and wide portions by using the laser head 4 a havinga relatively large laser irradiation width. Meanwhile, for portions inwhich concaves and convexes exist complicatedly in a narrow range on themolding surface 12, the portions having complicated shapes, can beirradiated evenly with the laser beam L by using the laser head 4 bhaving a relatively small laser irradiation width, and as a result, thedirt X can be removed cleanly.

The temperature of the molding surface 12 that is irradiated with thelaser beam L can be successively detected by the temperature sensor 3 c.An acceptable temperature is input and set to the control device 7 inadvance. The acceptable temperature is set to a predeterminedtemperature that does not reach the melting temperature of the mold 11.The irradiation with the laser beam L is suspended when the temperaturedetected by the temperature sensor 3 c exceeds the preset acceptabletemperature. With this configuration, even if malfunctions such as thereduction of the movement velocity or the stopping of the laser head 4occur due to unintentional factors, the molding surface 12 can beavoided from being overheated by the emitted laser beam L. As such, amalfunction that the molding surface 12 is thermally deformed orscratched by the laser beam L can be prevented.

After the cleaning of the mold 11 is finished, the outlet door 9 b isopened and the processing conveyor belt 10 b and the carrying-outconveyor belt 10 c are operated to move the cleaned mold 11 out of thecleaning booth 9. At this time, the inlet door 9 a is opened and thecarrying-in conveyor belt 10 a is operated to move the next mold 11 tobe cleaned from the outside to the inside of the cleaning booth 9 andposition the mold 11 at a predetermined position on the processingconveyor 10 b. In this way, the mold 11 is cleaned sequentially andcontinuously.

The invention claimed is:
 1. A mold cleaning system comprising: a laser oscillator; a laser head configured to irradiate a molding surface of a mold with a laser beam supplied from the laser oscillator; an arm configured to move the laser head freely in three dimensions; a control device configured to control motion of the arm; a database in which an identification mark assigned to each mold to be cleaned to identify the mold, and shape data of the molding surface of the mold to which the identification mark is assigned are stored in advance in association with each other; a mark detector configured to detect the identification mark; and a camera configured to obtain image data of the molding surface; wherein the shape data of the molding surface of the mold stored in the database is obtained on the basis of the identification mark assigned to the mold and detected by the mark detector when the mold is cleaned, and wherein, by controlling the motion of the arm on the basis of the obtained shape data, the laser head is moved along the molding surface while irradiating with the laser beam to clean the molding surface; and the mold cleaning system is configured to determine a cleaning state of the molding surface on the basis of the image data obtained by the camera, store the determined cleaning state and position information of the molding surface in the control device, and, for positions on the molding surface in which the determined cleaning state does not satisfy a preset standard, perform cleaning again by irradiating with the laser beam from the laser head.
 2. The mold cleaning system according to claim 1, further comprising a plurality of laser heads having different laser irradiation widths as the laser head, wherein the mold cleaning system is configured to perform cleaning for particular preset portions by using a laser head having a relatively small laser irradiation width or by using a laser head having a relatively large laser irradiation width with the laser head having a relatively small laser irradiation width.
 3. The mold cleaning system according to claim 1, further comprising a temperature sensor configured to successively detect a temperature of the molding surface that is irradiated with the laser beam, wherein the mold cleaning system is configured to suspend an irradiation with the laser beam when the temperature detected by the temperature sensor exceeds a preset acceptable temperature.
 4. The mold cleaning system according to claim 1, wherein the mold is a studless-tire vulcanization mold or a cast splicing mold for pneumatic tire vulcanization.
 5. The mold cleaning system according to claim 1, wherein the movement direction of the laser head and the irradiation direction of the laser beam are controlled while keeping the spacing between the tip of the laser head and the opposing molding surface constant. 